1. Field of the Invention
The present invention relates to a thin film transistor (“TFT”) array substrate and a method of fabricating the same, and more particularly, to a TFT array substrate in which a driving margin may be increased and a sufficiently large contact area between conductive materials may be provided in a contact portion, and a method of fabricating the TFT array substrate.
2. Description of the Related Art
A liquid crystal display (LCD) includes two opposing display panels and a liquid crystal layer interposed therebetween. Each display panel may use a transparent insulating substrate as a supporting substrate. A plurality of thin film patterns may be formed on the insulating substrate. A thin film pattern formation includes a material deposition and a mask process. However, a photolithography process may include multiple steps, such as photoresist coating, mask arrangement, exposure, baking, development, and cleaning, thus increasing the entire processing time and the manufacturing cost.
In order to reduce the number of mask processes, a lift-off method has been studied. More specifically, when a passivation film and a pixel electrode are formed on a TFT array substrate, the passivation film is patterned using a photoresist pattern, a conductive material is deposited on the entire surface of the TFT array substrate, and the photoresist pattern and the conductive material thereon are simultaneously removed using a photoresist stripper. The conductive material remaining on the substrate forms a pixel electrode.
The photoresist stripper may contact the sides or bottom of the photoresist pattern to remove the photoresist pattern covered with the conductive material. To prevent a pattern defect due to a residual portion of the photoresist pattern remaining on the substrate, the contact area of the photoresist pattern with the photoresist stripper should be sufficiently large. Specifically, the passivation film under the photoresist pattern should form a sufficiently large undercut under the inner side of the photoresist pattern. However, if the passivation film is over-etched to form such an undercut, an insulating film on a storage electrode may be over-etched and its thickness may become non-uniform, thus causing a reduction in a driving margin. Moreover, a data interconnection line may be damaged by over-etching, and etching of the data interconnection line in a contact area may cause contact failure.